4G0 THEODOR SCHWANN. 



THEODOR SCHWANN. 



Theodor Schwann, the distinguished founder of the animal-cell 

 theory, died on the 11th of January, 1882, in the seventy-second year 

 of his a^e, having been a Foreign Honorary Member of this Academy 

 for more than thirty years. His death followed closely upon that of 

 Schleiden, the almost equally celebrated founder of the vegetable-cell 

 theory, who died on the 23d of June, 1881. Thus death has asso- 

 ciated the two investigators whose labors gave to biology the first im- 

 pulse in the direction which it has since followed with such triumphant 

 results. 



Theodor Schwann was born in Neuss, Diisseldorf, on December 7, 

 1810. For five years following the completion of his medical studies, 

 he held the position of assistant to Johannes Miiller in Berlin. Dur- 

 ing the next nine years he occujiied the chair of anatomy in the 

 Catholic University of Louvain. In 1818 he was called to the Uni- 

 versity of Liege, where he remained till the time of his death, occupy- 

 ing in succession the chairs of anatomy and physiology. Schwann's 

 classical work, upon which his fame chiefly rests, was published, in 

 1839, under the title " Microscopical Researches into the Accordance 

 in the Structure and Growth of Animals and Plants." In this work 

 the observations of Schleiden upon vegetables were extended into the 

 animid kingdom, and the cell was recognized as the morphological unit 

 in animals as well as in plants. It is however less from a histological 

 than from a physiological point of view that Schwann's work is to be 

 regarded as marking an era in biological science. The conception of 

 cell life which he formed does not seem to have difi"cred much from that 

 of protoplasmic activity as now understood, but his views in regard to 

 the origin of cells have been entirely supplanted by those of more 

 recent investigators. The doctrine which has for its motto, " Omnis 

 ccllula e cellula," has taken the place of the theory of "organic crys- 

 tallization " of the cell from a " cytoblastema." 



These researches into cell-structure and growth, though by far the 

 most important work of Schwann, do not constitute his only title to 

 fame. He also pointed out the connection between the growth of or- 

 ganisms and tlie processes of fermentation and putrefaction, thus mark- 

 ing out a line of research whicli has since been followed with so much 

 success by Pasteur and others. He was likewise the first to study 

 muscular contraction as a physical process, and to express mathemati- 

 cally the f )rcc manif sted by the muscular fibres at different periods of 

 their contraction. Among his lesser contributions to physiology are 



